1,921 research outputs found
STM imaging of electronic waves on the surface of BiTe: topologically protected surface states and hexagonal warping effects
Scanning tunneling spectroscopy studies on high-quality BiTe crystals
exhibit perfect correspondence to ARPES data, hence enabling identification of
different regimes measured in the local density of states (LDOS). Oscillations
of LDOS near a step are analyzed. Within the main part of the surface band
oscillations are strongly damped, supporting the hypothesis of topological
protection. At higher energies, as the surface band becomes concave,
oscillations appear which disperse with a particular wave-vector that may
result from an unconventional hexagonal warping term.Comment: 4 pages, 4 figures. Revised manuscript with improved analysis and
figure
Interaction of marijuana and alcohol on fatal motor vehicle crash risk: a case–control study
Background:
Concurrent use of marijuana and alcohol in drivers is of increasing concern but its role in crash causation has not been well understood.
Methods:
Using a case–control design, we assessed the individual and joint effects of marijuana and alcohol use on fatal crash risk. Cases (n = 1944) were drivers fatally injured in motor vehicle crashes in the United States at specific times in 2006, 2007 and 2008. Controls (n = 7719) were drivers who participated in the 2007 National Roadside Survey of Alcohol and Drug Use by Drivers.
Results:
Overall, cases were significantly more likely than controls to test positive for marijuana (12.2% vs. 5.9%, p < 0.0001), alcohol (57.8% vs. 7.7%, p < 0.0001) and both marijuana and alcohol (8.9% vs. 0.8%, p < 0.0001). Compared to drivers testing negative for alcohol and marijuana, the adjusted odds ratios of fatal crash involvement were 16.33 [95% confidence interval (CI): 14.23, 18.75] for those testing positive for alcohol and negative for marijuana, 1.54 (95% CI: 1.16, 2.03) for those testing positive for marijuana and negative for alcohol, and 25.09 (95% CI: 17.97, 35.03) for those testing positive for both alcohol and marijuana.
Conclusions:
Alcohol use and marijuana use are each associated with significantly increased risks of fatal crash involvement. When alcohol and marijuana are used together, there exists a positive synergistic effect on fatal crash risk on the additive scale
Translocation Dynamics with Attractive Nanopore-Polymer Interactions
Using Langevin dynamics simulations, we investigate the influence of
polymer-pore interactions on the dynamics of biopolymer translocation through
nanopores. We find that an attractive interaction can significantly change the
translocation dynamics. This can be understood by examining the three
components of the total translocation time
corresponding to the initial filling of the pore, transfer of polymer from the
\textit{cis} side to the \textit{trans} side, and emptying of the pore,
respectively. We find that the dynamics for the last process of emptying of the
pore changes from non-activated to activated in nature as the strength of the
attractive interaction increases, and becomes the dominant
contribution to the total translocation time for strong attraction. This leads
to a new dependence of as a function of driving force and chain length.
Our results are in good agreement with recent experimental findings, and
provide a possible explanation for the different scaling behavior observed in
solid state nanopores {\it vs.} that for the natural -hemolysin
channel.Comment: 8 pages, 11 figure
Imaging nonequilibrium atomic vibrations with x-ray diffuse scattering
For over a century, x-ray scattering has been the most powerful tool for
determining the equilibrium structure of crystalline materials. Deviations from
perfect periodicity, for example due to thermal motion of the atoms, reduces
the intensity of the Bragg peaks as well as produces structure in the diffuse
scattering background. Analysis of the thermal diffuse scattering (TDS) had
been used to determine interatomic force constants and phonon dispersion in
relatively simple cases before inelastic neutron scattering became the
preferred technique to study lattice dynamics. With the advent of intense
synchrotron x-ray sources, there was a renewed interest in TDS for measuring
phonon dispersion. The relatively short x-ray pulses emanating from these
sources also enables the measurement of phonon dynamics in the time domain.
Prior experiments on nonequilibrium phonons were either limited by
time-resolution and/or to relatively long wavelength excitations. Here we
present the first images of nonequilibrium phonons throughout the Brillouin
zone in photoexcited III-V semiconductors, indium-phosphide and
indium-antimonide, using picosecond time-resolved diffuse scattering. In each
case, we find that the lattice remain out of equilibrium for several hundred
picoseconds up to nanoseconds after laser excitation. The non-equilibrium
population is dominated by transverse acoustic phonons which in InP are
directed along high-symmetry directions. The results have wide implications for
the detailed study of electron-phonon and phonon-phonon coupling in solids.Comment: 10 pages, 3 figure
Validity of oral fluid test for Delta-9-tetrahydrocannabinol in drivers using the 2013 National Roadside Survey Data
Background
Driving under the influence of marijuana is a serious traffic safety concern in the United States. Delta 9-tetrahydrocannabinol (THC) is the main active compound in marijuana. Although blood THC testing is a more accurate measure of THC-induced impairment, measuring THC in oral fluid is a less intrusive and less costly method of testing.
Methods
We examined whether the oral fluid THC test can be used as a valid alternative to the blood THC test using a sensitivity and specificity analysis and a logistic regression, and estimate the quantitative relationship between oral fluid THC concentration and blood THC concentration using a correlation analysis and a linear regression on the log-transformed THC concentrations. We used data from 4596 drivers who participated in the 2013 National Roadside Survey of Alcohol and Drug Use by Drivers and for whom THC testing results from both oral fluid and whole blood samples were available.
Results
Overall, 8.9% and 9.4% of the participants tested positive for THC in oral fluid and whole blood samples, respectively. Using blood test as the reference criterion, oral fluid test for THC positivity showed a sensitivity of 79.4% (95% CI: 75.2%, 83.1%) and a specificity of 98.3% (95% CI: 97.9%, 98.7%). The log-transformed oral fluid THC concentration accounted for about 29% of the variation in the log-transformed blood THC concentration. That is, there is still 71% of the variation in the log-transformed blood THC concentration unexplained by the log-transformed oral fluid THC concentration. Back-transforming to the original scale, we estimated that each 10% increase in the oral fluid THC concentration was associated with a 2.4% (95% CI: 2.1%, 2.8%) increase in the blood THC concentration.
Conclusions
The oral fluid test is a highly valid method for detecting the presence of THC in the blood but cannot be used to accurately measure the blood THC concentration
Short Term Development and Fate of MGE-Like Neural Progenitor Cells in Jaundiced and Non-Jaundiced Rat Brain
A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Neonatal hyperbilirubinemia targets specific brain regions and can lead to kernicterus. One of the most debilitating symptoms of kernicterus is dystonia, which results from bilirubin toxicity to the globus pallidus (GP). Stem cell transplantation into the GP to replace lost neurons and restore basal ganglia circuits function is a potential therapeutic strategy to treat dystonia in kernicterus. In this study we transplanted human medial ganglionic eminence (MGE)-like neural progenitor cells (NPCs) that we differentiated into a primarily gamma-aminobutyric acid (GABA)ergic phenotype, into the GP of non-immunosuppressed jaundiced (jj) and non-jaundiced (Nj) rats. We assessed the survival and development of graft cells at three time-points post-transplantation. While grafted MGE-like NPCs survived and generated abundant fibers in both jj and Nj brains, NPC survival was greater in the jj brain. These results were consistent with our previous finding that excitatory spinal interneuron-like NPCs exhibited a higher survival rate in the jj brain than in the Nj brain. Our findings further support our hypothesis that slightly elevated bilirubin levels in the jj brain served as an antioxidant and immunosuppressant to protect the transplanted cells. We also identified graft fibers growing toward brain regions that receive projections from the GP, as well as host fibers extending toward the graft. These promising findings suggest that MGE-like NPCs may have the capacity to restore the circuits connecting GP and other nuclei.NIH Center of Biomedical Research Excellence program project P20 GM104936Children's Mercy HospitalRonald D. Deffenbaugh FoundationKansas Intellectual and Developmental Disabilities Research Center HD09021
Critical Enzymatic Functions of FTO in Obesity and Cancer
Fat mass and obesity-associated protein (FTO) single-nucleotide polymorphisms (SNPs) have been linked to increased body mass and obesity in humans by genome-wide association studies (GWAS) since 2007. Although some recent studies suggest that the obesity-related SNPs in FTO influence obesity susceptibility likely through altering the expression of the adjacent genes such as IRX3 and RPGRIP1L, rather than FTO itself, a solid link between the SNP risk genotype and the increased FTO expression in both human blood cells and fibroblasts has been reported. Moreover, multiple lines of evidence have demonstrated that FTO does play a critical role in the regulation of fat mass, adipogenesis, and body weight. Epidemiology studies also showed a strong association of FTO SNPs and overweight/obesity with increased risk of various types of cancers. As the first identified messenger RNA N6-methyladenosine (m6A) demethylase, FTO has been shown recently to play m6A-dependent roles in adipogenesis and tumorigenesis (especially in the development of leukemia and glioblastoma). Given the critical roles of FTO in cancers, the development of selective and effective inhibitors targeting FTO holds potential to treat cancers. This mini review discusses the roles and underlying molecular mechanisms of FTO in both obesity and cancers, and also summarizes recent advances in the development of FTO inhibitors
SeaWiFS technical report series. Volume 9: The simulated SeaWiFS data set, version 1
Data system development activities for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) must begin well before the scheduled 1994 launch. To assist in these activities, it is essential to develop a simulated SeaWiFS data set as soon as possible. Realism is of paramount importance in this data set, including SeaWiFS spectral bands, orbital and scanning characteristics, and known data structures. Development of the simulated data set can assist in identification of problem areas that can be addressed and solved before the actual data are received. This paper describes the creation of the first version of the simulated SeaWiFS data set. The data set includes the spectral band, orbital, and scanning characteristics of the SeaWiFS sensor and SeaStar spacecraft. The information is output in the data structure as it is stored onboard. Thus, it is a level-0 data set which can be taken from start to finish through a prototype data system. The data set is complete and correct at the time of printing, although the values in the telemetry fields are left blank. The structure of the telemetry fields, however, is incorporated. Also, no account for clouds has been included. However, this version facilitates early prototyping activities by the SeaWiFS data system, providing a realistic data set to assess performance
Comparison of 6-mm and 11-mm dental implants in the posterior region supporting fixed dental prostheses:5-year results of an open multicenter randomized controlled trial
OBJECTIVE: The aim of this multicenter, randomized controlled trial was to compare the clinical and radiographic outcomes of 6-mm or 11-mm implants, placed in the posterior maxilla and mandible, during a 5-year follow-up period. MATERIALS AND METHODS: Ninety-five patients with adequate bone height for 11-mm implants, were randomly allocated to a 6-mm group (test group with short implants) or an 11-mm group (control group with standard-length implants). Two or three implants of the same length were placed in each patient and after 6 weeks loaded with a splinted provisional restoration. This was followed by definitive splinted restoration 6 months after implant placement. Clinical and radiographic parameters, including the occurrence of complications were recorded. RESULTS: A total of 49 patients were enrolled to receive 6-mm implants (n = 108) and 46 patients to receive 11-mm implants (n = 101). Three implants (two of 6 mm and one of 11 mm in length) were lost before loading and one 6-mm implant after 15 months of function, and one 11-mm implant was lost during the first year of function. The 5-year survival rates were 96.0% and 98.9% in the 6-mm and 11-mm group, respectively. The mean marginal bone level changes 5 years post-loading were 0.01 ± 0.45 mm (bone gain) in the 6-mm group and -0.12 ± 0.93 mm (bone loss) in the 11-mm group (p = .7670). Clinical parameters, including plaque, bleeding on probing and pocket probing depth were not significantly different between the groups, and also technical complications were low. CONCLUSION: The clinical and radiographic outcomes of 6-mm short and 11-mm standard-length implants were not different during a 5-year evaluation period
Gravitomagnetism and spinor quantum mechanics
We give a systematic treatment of a spin 1/2 particle in a combined
electromagnetic field and a weak gravitational field that is produced by a
slowly moving matter source. This paper continues previous work on a spin zero
particle, but it is largely self-contained and may serve as an introduction to
spinors in a Riemann space. The analysis is based on the Dirac equation
expressed in generally covariant form and coupled minimally to the
electromagnetic field. The restriction to a slowly moving matter source, such
as the earth, allows us to describe the gravitational field by a
gravitoelectric (Newtonian) potential and a gravitomagnetic (frame-dragging)
vector potential, the existence of which has recently been experimentally
verified. Our main interest is the coupling of the orbital and spin angular
momenta of the particle to the gravitomagnetic field. Specifically we calculate
the gravitational gyromagnetic ratio as gsubg=1 ; this is to be compared with
the electromagnetic gyromagnetic ratio of gsube=2 for a Dirac electron.Comment: 12 pages, 1 figur
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